Light Intensity And Photosynthesis Essay

784 Words4 Pages
Haya Al-Khater
Mr. Gurney
Biology HL
December 1, 2014

The Effect of Light intensity on rate of photosynthesis

Research question-
How does light intensity affect the rate of photosynthesis in Spinach leaves (Spinacia oleracea)?

Hypothesis- My hypothesis is that light intensity and photosynthesis rate have a positive correlation. Meaning that as light intensity increases, photosynthesis rate will increase. This is because as light intensity increase, the rate of light-dependent reactions increase since light dependent reactions use light as an energy source. When light hits the surface of the leaf, it is absorbed by chlorophyll pigments. The light dependent reaction takes place in the chloroplast, more specifically the thylakoid membrane.
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Apply nail varnish to the leafs surface.
4. When the nail varnish dries, peel off the layer of nail varnish using sellotape and place it on a transparent slide.
5. Look at the layer of varnish using a magnifying glass and mark the stomata using a think marker.
6. Place the nail varnish coat back onto the leaf.
7. Using a hole punch, cut 10 uniform leaf discs from the same leaf the nail varnish coating is on.
8. Use the marks of the stomata as guidance, make sure one stoma is in one leaf disc and do not cut through any major veins in the leaf or cut through a stoma.
9. Remove the plunger from the syringe barrel and place the ten leaf discs into the syringe barrel.
10. Place the plunger back into the syringe barrel then carefully push the plunger down until there are 3cm3 of air are left inside (make you sure no leaves are crushed)
11. Pull 5cm3 of Sodium hydrogen carbonate into the syringe. In the case of the leaf discs being stuck on the sides of the barrel, tap the syringe to suspend them in the solution.
12. Place your figure on the opening of the syringe, pull back the syringe to create a vacuum.
13. Hold the plunger back for the 10 seconds then slowly release the vacuum.
14. Repeat steps 12-13 until all the ten discs

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